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[InstCombine] fix bug in pow expansion 

There at least one other bug related to pow -> sqrt transforms:
http://lists.llvm.org/pipermail/llvm-dev/2020-September/145051.html
...but we probably can't solve that without fixing this first.
This commit is contained in:
Sanjay Patel 2020-09-15 09:27:16 -04:00
parent 7ffc9aa538
commit aa57c1c967
2 changed files with 6 additions and 13 deletions
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2
llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
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@ -1748,6 +1748,8 @@ Value *LibCallSimplifier::optimizePow(CallInst *Pow, IRBuilderBase &B) {
Sqrt = getSqrtCall(Base, Pow->getCalledFunction()->getAttributes(),
Pow->doesNotAccessMemory(), M, B, TLI);
if (!Sqrt)
return nullptr;
}
// We will memoize intermediate products of the Addition Chain.

17
llvm/test/Transforms/InstCombine/pow-4.ll
View File

@ -152,7 +152,6 @@ define double @test_simplify_neg_16_5(double %x) {
}
; pow(x, 16.5) with double
; FIXME: This is wrong without sqrt.
define double @test_simplify_16_5_libcall(double %x) {
; SQRT-LABEL: @test_simplify_16_5_libcall(
@ -165,18 +164,14 @@ define double @test_simplify_16_5_libcall(double %x) {
; SQRT-NEXT: ret double [[TMP4]]
;
; NOSQRT-LABEL: @test_simplify_16_5_libcall(
; NOSQRT-NEXT: [[SQUARE:%.*]] = fmul fast double [[X:%.*]], [[X]]
; NOSQRT-NEXT: [[TMP1:%.*]] = fmul fast double [[SQUARE]], [[SQUARE]]
; NOSQRT-NEXT: [[TMP2:%.*]] = fmul fast double [[TMP1]], [[TMP1]]
; NOSQRT-NEXT: [[TMP3:%.*]] = fmul fast double [[TMP2]], [[TMP2]]
; NOSQRT-NEXT: ret double [[TMP3]]
; NOSQRT-NEXT: [[TMP1:%.*]] = call fast double @pow(double [[X:%.*]], double 1.650000e+01)
; NOSQRT-NEXT: ret double [[TMP1]]
;
%1 = call fast double @pow(double %x, double 1.650000e+01)
ret double %1
}
; pow(x, -16.5) with double
; FIXME: This is wrong without sqrt.
define double @test_simplify_neg_16_5_libcall(double %x) {
; SQRT-LABEL: @test_simplify_neg_16_5_libcall(
@ -190,12 +185,8 @@ define double @test_simplify_neg_16_5_libcall(double %x) {
; SQRT-NEXT: ret double [[RECIPROCAL]]
;
; NOSQRT-LABEL: @test_simplify_neg_16_5_libcall(
; NOSQRT-NEXT: [[SQUARE:%.*]] = fmul fast double [[X:%.*]], [[X]]
; NOSQRT-NEXT: [[TMP1:%.*]] = fmul fast double [[SQUARE]], [[SQUARE]]
; NOSQRT-NEXT: [[TMP2:%.*]] = fmul fast double [[TMP1]], [[TMP1]]
; NOSQRT-NEXT: [[TMP3:%.*]] = fmul fast double [[TMP2]], [[TMP2]]
; NOSQRT-NEXT: [[RECIPROCAL:%.*]] = fdiv fast double 1.000000e+00, [[TMP3]]
; NOSQRT-NEXT: ret double [[RECIPROCAL]]
; NOSQRT-NEXT: [[TMP1:%.*]] = call fast double @pow(double [[X:%.*]], double -1.650000e+01)
; NOSQRT-NEXT: ret double [[TMP1]]
;
%1 = call fast double @pow(double %x, double -1.650000e+01)
ret double %1